Simple true-time-delay generator for optical control of phased array antenna

A true time delay generator, comprising

• (a) first and second end walls disposed substantially parallel to each other and forming a cavity therebetween, the first end wall having a first plurality of mirrors formed thereon and the second end wall having a second plurality of mirrors formed thereon to face the first plurality of mirrors;
• (b) an intermediate wall disposed between said first and second end walls and being substantially parallel thereto to form a first chamber and a second chamber in said cavity, said intermediate wall having a third and a fourth plurality of mirrors formed on opposite sides thereof to face respectively the first plurality of mirrors of said first end wall and said second plurality of mirrors of said second end wall, said intermediate wall having a series of apertures for passage of the input light beams from the first chamber to the second chamber;
• and
• (c) displacement means for displacing one of (1) said intermediate wall relative to said first and second end walls and (2) said first and second end walls relative to said intermediate wall, so that an area of the first and second chambers is variable for changing a time delay of the optical path of the input light beams in the cavity.

Method of true time delay for optical control of a phased array antenna system having an array of antenna elements arrayed in a first dimension and a second dimension and having a number N of antenna elements in said first dimension and a number M of antenna elements in said second dimension, comprising the steps of:

• (a) inputting a set of input light beams, corresponding to said number N of antenna elements in said first dimension, into a first chamber of a first delay unit so as to impinge on one of a plurality of third mirrors of an intermediate wall of said first delay unit;
• (b) reflecting said set of input light beams between said third mirrors and a plurality of first mirrors of said first delay unit;
• (for the nth beam, 1≦n≦N, n total reflections are made in the first chamber)
• (c) passing said input light beams through a plurality of apertures formed in said first delay unit into a second chamber of said first delay unit;
• (d) reflecting said input light beams within said second chamber between fourth mirrors formed on said intermediate wall and second mirrors formed on said second wall of said first delay unit;
• (for the nth beam N-n total refections are made in the second chamber)
• (e) passing said input light beams out of said second chamber of said first time delay unit to provide an output comprising a first series of light beams, N in number, delayed relative to one another with an equal amount of time delay in said first dimension between each two consecutive light beams of said first series of light beams;
• (f) splitting each light beam of said first series of light beams to provide an output comprising N groups of M light beams;
• (g) providing said N groups of M light beams to respectively a first chamber of N delay generator units of a second time delay means so as to impinge on one of a plurality of third mirrors formed on an intermediate wall of said respective ones of said N delay generator units;
• (h) reflecting said N groups of M light beams between said third mirrors and first mirrors formed on a first wall of said respective ones of said N delay generator units;
• (i) passing said N groups of M light beams through said apertures of said respective ones of said N delay generator units into a second chamber of said respective ones of said N delay generator units;
• (j) reflect said N groups of M light beams between fourth mirrors formed on a second wall of said respective ones of said N delay generator units and said second mirrors of said respective ones of said N delay generator units;
• and
• (k) passing said N groups of M light beams out of said second chamber of said respective ones of said N delay generator units.